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Software for evaluation of data from CVVOZE laboratory
Petráček, Dominik ; Šimek, David (referee) ; Pikula, Stanislav (advisor)
The diploma thesis is focused on the innovation of partially user-unsuitable software which is used in the CVVOZE short-circuit laboratory for the evaluation of testing of switching and protection devices. The introductory part of the work presents a technical laboratory, which is used for research and development in the field of electrical devices with possibility of testing of short circuits and over-currents. At the first part of thesis, there is made a description of the technical laboratory. The following past is a chapter with basic introduction of tested devices and standard testing conditions of electrical devices in the laboratory. Then following a description of the original evaluation software is made and its shortcomings are pointed out. The practical part is devoted to the creating in LabVIEW, implementation and verification of the functionality of the new evaluation software.
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Diagnostics of medium voltage and high voltage circuit breakers
Kapalla, Alexej ; Šimek, David (referee) ; Dostál, Lukáš (advisor)
This bachelor work is focused on medium-voltage and high-voltage circuit breakers and their diagnostics. The thesis presents the history of HV circuit breakers and their main division. Subsequently, the relevant standards are listed in the work and diagnostics of the MV circuit breaker VD4 and the HV circuit breaker S1-245 from AEG is performed. In case of the VD4 circuit breaker, a new and used circuit breaker was diagnosed. The measured values are then compared and the impact of usage is shown. The work describes the measurement of main contact resistance, insulation resistance, closing and opening times and vacuum quality.
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Investigation of the durability of low voltage switching apparatuses construction parts
Dalecký, Jan ; Dostál, Lukáš (referee) ; Šimek, David (advisor)
This thesis deals with study of durability of low voltage switching devices components. It describes components of circuit breaker and low voltage contactor and contains function models of these devices in various states. Based on model analysis, components that can get worn, damaged or destroyed were selected. Further practical experiments on two samples of circuit breakers from different manufacturers were executed to verify their technical parameters and parts durability. Failure of some components can cause switching device to malfunction.
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USING MODERN NUMERIC METHODS IN DESIGN OF LOW VOLTAGE CIRCUIT BREAKERS
Dostál, Lukáš ; Hüttner, Ľudovít (referee) ; Petráček, Miloš (referee) ; Aubrecht, Vladimír (advisor)
The theses is focused on efficient use of numerical methods in development of low-voltage switching devices, namely to create a physically correct and reliable numerical model of the temperature field to find an application in the design of the current path of a device for various operating conditions. The creation of this numerical model requires not only correct inclusion of all modes of heat transfer - conduction, convection and radiation, but also correct solution of problematic transient resistance - both electrical and thermal in electrical contacts at different stages of usage. Therefore an essential part of the theses forms a thorough experimental analysis of the necessary material properties and dependencies which forms input data for the numerical model that is based on the finite volume method. The last part of the theses deals with debugging and verification of numerical model to correspond with experimentally obtained data. The result of the theses is the numerical model which is able to solve correctly both steady and various transient states of swiching devices.
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Evaluation of pressure conditions in the quenching chamber of low-voltage device
Nevrzal, Filip ; Vávra, Daniel (referee) ; Valenta, Jiří (advisor)
In this master’s thesis there is firstly conducted research about pressure measurement. Next there is mathematical description of thermodynamic conditions in used testing chamber by using magnetohydrodynamic and Maxwell equations. Next chapter deals with testing chamber itself, more precisely with function, model and changes done to it. In practical part there are data measured by used sensors, which are also closer described in this chapter. In next chapter there is comparison of reaction times of used sensors and their frequency specters, obtaining using fast Fourier transformation. Second to last chapter introduces very measurement on the real device and in the last chapter these data are analyzed and more closely described.
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Analysis Of Contact Disconnection In A Low
Voltage Circuit Breaker
Mačák, Martin
This work deals with a simulation of plasma phenomenon and with a simulation of an arc ingnition between contacts in a low voltage circuit breaker. Simulations were made in Ansys Fluent with the usage of MHD (Magnetohydrodynamic) add-on module and additional UDFs (User Defined Functions). Mathematical model presented in this work connects electric and magnetic field, which is not possible in Ansys Fluent by default.
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Contact erosion of switching devices
Píška, Jakub ; Šimek, David (referee) ; Valenta, Jiří (advisor)
This bachelor thesis deals with the erosion of contacts, as one of the negative phenomena affecting contacts of switchgears. In its first part, it briefly summarizes the other negative influences that must be considered when designing switching devices. In the following part, the physical mechanism of erosion and the primary criterion of assessment - weight loss are approached. The last and main part of the work deals with design of the contact system for comparing this loss for for frequently used materials and testing on a real switchgear. After the tests, the results were analyzed primarily from the perspective of ignition angles, the polarities of the current pulse and the current flowing through the arc. Taking into account the influence of the material composition, the size of the contacts and the presence of the arc-runner.
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Analysis and evaluation of technical systems of motor operators of circuit breakers
Hurbanič, Jakub ; Valenta, Jiří (referee) ; Dostál, Lukáš (advisor)
This bachelor thesis was created as a overview and analysis of drive systems for moulded case power circuit breakers. There si an introduction to motor operators and their possible use with remote control and use in future in name of digitalization and elektrification. Also there is listed an analysis of opertors depending on the method of installation, switching power and the operator itself i.e. electric motor or electromagnet. There is mentioned the possibilities of controll and power supply of these operators and the positions of circuit breaker. In the end a small market analysis is executed and a short chapter dealing with measurment of electric motor operator in OEZ s.r.o. company.
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Contact erosion of switchgear under real conditions
Holoubek, Josef ; Bušov, Bohuslav (referee) ; Valenta, Jiří (advisor)
This bachelor thesis is focused on the material loss - contacts erosion during switching process of the switchgears. First part is focused on the switchgears generally, their dividing and functions. Then there is closer look on the contacts of switchgears and what is necessary to be considered during their designing a operating. In this part there is also section devoted to the theory of the contacts erosion including the formulas for material loss calculation, which I found in existing literature. Practical part is focused on the contact system model and the measuring performed on this model. Measuring was also performed on the real switchgears for common use. There is also part devoted to this measuring. In the last part of thesis the analyze of the measured values is performed.
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Determination of the Temperature Field in a Real Circuit Breaker
Pěček, Dominik ; Aubrecht, Vladimír (referee) ; Kloc, Petr (advisor)
This master thesis deals with determination of temperature field in a real circuit breaker. This issue is solved by analysis of measured emission spectra at selected points of the circuit breaker. Spectral line ratios and Boltzmann plot are used for calculation of temperature. These methods are based on elemental analysis of plasma. The main result is finding significant changing of chemical composition of plasma beyond determination of temperature field.
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